Bug 2312076 (CVE-2024-46688)

Summary: CVE-2024-46688 kernel: erofs: fix out-of-bound access when z_erofs_gbuf_growsize() partially fails
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
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OS: Linux   
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Bug Depends On: 2312206    
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Description OSIDB Bzimport 2024-09-13 06:21:11 UTC 
In the Linux kernel, the following vulnerability has been resolved:

erofs: fix out-of-bound access when z_erofs_gbuf_growsize() partially fails

If z_erofs_gbuf_growsize() partially fails on a global buffer due to
memory allocation failure or fault injection (as reported by syzbot [1]),
new pages need to be freed by comparing to the existing pages to avoid
memory leaks.

However, the old gbuf->pages[] array may not be large enough, which can
lead to null-ptr-deref or out-of-bound access.

Fix this by checking against gbuf->nrpages in advance.

[1] https://lore.kernel.org/r/000000000000f7b96e062018c6e3@google.com
Comment 1 Michal Findra 2024-09-13 14:35:37 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2024091338-CVE-2024-46688-7a5a@gregkh/T